A plurality of combustors 51 of a gas turbine are mounted annularly around a casing 50 of the gas turbine, as shown in FIG. 5. Each combustor 51 has a pilot nozzle 52, and a plurality of main nozzles 53 arranged annularly around the pilot nozzle 52, and the respective combustors 51 are annularly supported on a nozzle pipe base 56, as shown in FIG. 6(a). In the case of a dual mode in which fuel is switched between oil fuel and gas fuel, the main nozzle 53 is of a double structure consisting of a central pipe 54 for passage of oil fuel, and an outer pipe 55 disposed on the outer periphery of the central pipe 54 and designed for passage of gas fuel. The pilot nozzle 52 also has a similar double structure.
Patent Document 1: U.S. Pat. No. 4,258,544
Patent Document 2: Japanese Patent No. 3495730